gcd exgcd[通俗易懂]

#include <bits/stdc++.h>
#define _ ios_base::sync_with_stdio(0);cin.tie(0);

#define INF 0x3f3f3f3f
#define eps 1e-5

typedef long long LL;
const double pi = acos(-1.0);
const long long mod = 25 * 1E8;
using namespace std;

//O(log max(a,b))
int gcd(int a,int b)
{
    return !b ? a : gcd(b,a % b);
}

//|x| <= b && |y| <= a
int exgcd(int a,int b,int &x,int &y)
{
    int d = a;
    if(b != 0)
    {
        d = exgcd(b,a % b,y,x);
        y -= (a / b) * x;
    }
    else
    {
        x = 1;
        y = 0;
    }
    return d;
}

int main()
{
    //freopen("input.txt","r",stdin);
    //freopen("output.txt","w",stdout);
    ios_base::sync_with_stdio(0);cin.tie(0);

    return 0;

}